Reciprocating tools that are motor driven, such as saber saws, larger reciprocating saws and the like are usually driven by electric motors that have a rotating output shaft. The rotating motion is translated into reciprocating motion for moving a saw blade or the like in a reciprocating manner. Various approaches have been developed which translate the rotational motion into reciprocating motion. A common approach is the incorporation of a wobble plate drive.
A “wobble plate” assembly is a configuration wherein a shaft has an angled portion on which an arm is mounted through a ball bearing assembly. The arm is slidingly positioned within a portion of a plunger assembly. As the angled portion of the shaft rotates, the arm translates the rotation of the shaft into a reciprocating movement of the plunger assembly. One example of a reciprocating tool which incorporates a wobble plate drive is U.S. Pat. No. 7,707,729, which issued on May 4, 2010, the entire contents of which are herein incorporated by reference.
As the plunger assembly moves along an axis, a significant amount of momentum is created. All of this momentum is absorbed by the tool as the plunger assembly reverses direction. Thus, a user of a reciprocating tool incorporating a wobble plate drive must contend with a powerfully vibrating device. In order to make such reciprocating tools more controllable, reciprocating tools such as the device in the '729 patent incorporate a counterweight which is driven by a secondary wobble plate in a direction opposite to the direction of the plunger assembly. While the incorporation of a secondary wobble plate and counterweight is effective, such systems can be bulky and expensive.
Other devices for changing rotational movement to reciprocating movement include scotch yoke mechanism and crank sliders. Such devices are disclosed in U.S. Pat. No. 6,357,125 which issued on Mar. 19, 2002, and U.S. Patent Publication No. 2008/0134855, which was published on Jun. 12, 2008, the entire contents of which are both herein incorporated by reference. These systems also suffer from increased bulkiness.
A need exists for a reciprocating tool which reduces vibration of a wobble plate drive. A further need exists for a reciprocating tool which reduces vibration of a wobble plate drive which does not rely upon bulky assemblies. A system which reduces vibrations in a reciprocating tool while reducing costs associated with vibration reduction would be further beneficial.